docs: def validate_proxy_granting_ticket(pgt, target_service):
      """
      Validate a proxy granting ticket string. Return an ordered pair
      containing a ``ProxyTicket``, or a ``ValidationError`` if ticket
      validation failed.
      """
      logger.debug("Proxy ticket request received for %s using %s" % (target_service, pgt))
  
      pgt = ProxyGrantingTicket.objects.validate_ticket(pgt, target_service)
      pt = ProxyTicket.objects.create_ticket(service=target_service, user=pgt.user, granted_by_pgt=pgt)
      return pt